CN1849278A - Coating material for green sheet, green sheet, method for producing green sheet, and method for producing electronic component - Google Patents

Abstract

Provided are a green sheet coating material, a green sheet and a method, wherein the green sheet coating material can produce a green sheet having no pin holes, excellent surface smoothness and strength enough to resist peeling from a support even though the green sheet is extremely thin, and is suitable for thinning and multilayering of electronic parts. The present invention provides a green sheet coating material containing a ceramic powder, a binder resin containing a butyral resin as a main component, and a solvent. The solvent contains a 1 st solvent having an SP value of 10 or more, which is a numerical value of a solubility parameter for the binder resin, and a 2 nd solvent having an SP value of 8 or more but less than 10. The coating material contains 20 to 60 mass%, preferably 25 to 60 mass% of the No. 2 solvent with respect to 100 mass% of the total mass of the solvents.

Description

Coating material for green sheet, green sheet, method for producing green sheet, and method for producing electronic component

technical field

The present invention relates to a paint for green sheets, a green sheet, a method for preparing a green sheet, and a method for preparing an electronic component. More specifically, it relates to a paint, a green sheet, and a method, wherein the paint can prepare a Thin green sheets with excellent surface smoothness and no pinholes are suitable for thinning and multilayering of electronic components.

Background technique

In recent years, along with the miniaturization of various electrical appliances, the miniaturization and performance improvement of electronic components contained in the electrical appliances have been advancing. As one of the electronic components, there are ceramic electronic components such as CR built-in substrates and multilayer ceramic capacitors, and these ceramic electronic components are also being reduced in size and improved in performance.

In order to promote the miniaturization and high capacity of such ceramic electronic components, it is strongly required to reduce the thickness of the dielectric layer. Recently, the thickness of the dielectric green sheet constituting the dielectric layer is several micrometers or less.

In order to prepare ceramic green sheets, usually first prepare ceramic powder, binder (acrylic resin, butyral resin, etc.), plasticizer (phthalates, glycols, adipic acid, Phosphate esters) and organic solvents (toluene, MEK, acetone, etc.) Then, this ceramic paint is applied on a carrier sheet (a support made of PET or PP) using a doctor blade method or the like, followed by heating and drying.

In addition, in recent years, preparation of a ceramic suspension in which a ceramic powder and a binder are mixed in a solvent, extrusion molding of the suspension to obtain a film-like molded article, and preparation of the molded article by biaxial stretching have been conducted.

Specifically, a method for producing a multilayer ceramic capacitor using the above-mentioned ceramic green sheet is described. On the ceramic green sheet, a conductive paste for internal electrodes containing metal powder and a binder is printed in a predetermined pattern and dried. Internal electrode patterns are formed. Thereafter, the green sheet is peeled from the carrier sheet and laminated to a desired number of layers. Here, a method of peeling the green sheet from the carrier sheet before lamination and a method of peeling the carrier sheet after lamination were considered, but there was no significant difference. Finally, the laminate was cut into sheets to make green sheets. After sintering these green sheets, external electrodes are formed to produce electronic components such as multilayer ceramic capacitors.

When producing a multilayer ceramic capacitor, the interlayer thickness of the sheet on which the internal electrodes are formed is in the range of approximately 3 μm to 100 μm based on the desired capacitance required for the capacitor. In addition, in the multilayer ceramic capacitor, a portion where the internal electrodes are not formed is formed on the outer portion in the lamination direction of the capacitor chips.

Generally, as the thickness of the green sheet becomes thinner, the surface smoothness of the sheet decreases, making lamination difficult, which is a problem.

In recent years, along with the miniaturization of electric appliances, the miniaturization of electronic components used therein has rapidly progressed. In multilayer electronic components typified by multilayer ceramic capacitors, the number of layers to be laminated is rapidly increasing and interlayer thicknesses are becoming thinner. In response to this technological trend, the thickness of the green sheet, which determines the interlayer thickness, is changing from 3 μm or less to 2 μm or less. Therefore, in the manufacturing process of multilayer ceramic capacitors, it is necessary to handle extremely thin green sheets, and it is necessary to design very high physical properties of the green sheets.

The properties required for the physical properties of such an ultra-thin green sheet include sheet strength, flexibility, smoothness, adhesion during lamination, handleability (electrostatic properties), etc., and a high-dimensional balance is also required. .

In particular, when the sheet becomes thinner, the influence of the thickness on the roughness (concave-convex) of the sheet surface cannot be ignored. That is, changes in the surface state that do not need to be considered in thick sheets vary in thin sheets as the sheet thickness itself changes. The concave part with rough surface is not resistant to the applied voltage during sintering, which will cause a short circuit. For this reason, the production of a sheet with a smooth surface (=small change in surface roughness) and uniform thickness is an indispensable key technology in the production of multilayer chip capacitors.

It should be noted that, as shown in the following Patent Document 1, it is known that polyvinyl butyral resin with a degree of polymerization of 1000 or more is used as a binder in order to eliminate short-circuit defects in a slurry for green sheets containing an aqueous solvent. agent technology.

However, in Patent Document 1, not only is there no attempt to make the organic solvent-based green sheet thinner, but the surface flatness decreases as the thickness of the green sheet becomes thinner, making lamination difficult, which is a problem.

Patent Document 2 discloses a technique of using a solvent with a fast evaporation rate in order to accelerate the evaporation rate and improve the surface properties of the sheet. However, although the method of accelerating the evaporation rate is effective for obtaining a thick sheet, it has the side effect of deteriorating the surface property when the sheet is thinned.

As described in Patent Document 3 below, there is known an invention in which the blending composition ratio of the sheet, defoaming conditions, and drying temperature conditions are specified in the water-based paint.

However, in this technique, there is a possibility that a sheet with desired physical properties cannot be obtained due to the limitation of the composition, and the addition of a defoaming step makes the process complicated.

As described in Patent Document 4 below, a technique for improving surface properties of a rolled sheet is known.

However, in this technique, when the sheet is chemically grown in a thin layer, the sheet may be damaged due to pressurization.

Patent Document 1: Japanese Unexamined Patent Publication No. 6-206756

Patent Document 2: Patent Publication No. 2866137

Patent Document 3: JP-A-2000-335971

Patent Document 4: JP-A-2001-114568

Contents of the invention

The problem to be solved by the invention

The object of the present invention is to provide a coating material for a green sheet, a green sheet, and a method, wherein the coating material can produce a green sheet that is extremely thin but has strength capable of withstanding peeling from a support, and has an excellent surface smoothness, needle-free Green sheet with holes, suitable for thinning and multilayering of electronic components.

Solution to the problem

In order to achieve the above object, the green sheet coating material according to the present invention contains ceramic powder, a binder resin mainly composed of a butyral resin, and a solvent, and is characterized in that:

The solvent contains a first solvent having an SP value of 10 or more as a solubility parameter, and a second solvent having an SP value of 8 or more but less than 10,

The second solvent is contained in an amount of 20 to 60% by mass, preferably 25 to 60% by mass, based on 100% by mass of the total mass of the above solvents.

The paint composition using butyral-based resins uses highly polar alcohols as the main component in consideration of the solubility of the resin in solvents. In contrast, the dispersant used in the coating material according to the present invention has higher solubility than the second solvent. Therefore, by adjusting the polarity of the solvent so that the aggregation of the pigment does not occur in the paint, the dispersion of the pigment can be improved, and a sheet with excellent surface properties can be prepared.

That is, by making the solvent component in the paint have a wide polar range, it is possible to achieve both the solubility of the resin and the solubility of the dispersant. As a result, both the resin and the pigment became a paint with good dispersibility, and the surface became smooth when formed into a sheet. In addition, since the surface roughness of the sheet is reduced to be very small compared to the interlayer thickness, the interlayer thickness can be reduced (layer thinning), and further multilayer and miniaturized electronic components can be achieved.

For example, the thickness of the sintered dielectric layer (sintered green sheet) can be reduced to 5 μm or less, preferably 3 μm or less, more preferably 2 μm or less. Alternatively, the number of laminations may be increased. Furthermore, defects such as short circuits can be reduced.

Among the solvents, the mass ratio of the second solvent to the first solvent is preferably 0.2 to 2.0, more preferably 0.5 to 1.5.

If the mass ratio of the second solvent is too small, the surface smoothness will decrease due to the decrease in the solubility of the dispersant in the solvent, etc., and if the mass ratio is too large, the surface smoothness will decrease due to the decrease in the solubility of the resin in the solvent.

The coating material of the present invention preferably further contains a dispersant, and the above-mentioned dispersant is a polyethylene glycol-based anionic dispersant. In addition, the SP value of the dispersant is preferably 8-9. Such a dispersant has good solubility in the second solvent, resulting in improved dispersibility.

Preferably, the first solvent is an alcohol, and the second solvent contains at least one of ketones, esters, and aromatics. In this case, it is preferable that the above-mentioned first solvent is at least one selected from methanol, ethanol, propanol, and butanol, and that the above-mentioned second solvent contains a solvent selected from methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, and butyl acetate. At least one of esters, toluene, and xylene.

Preferably, the above-mentioned butyral resin is polybutyral resin, the polymerization degree of the above-mentioned polybutyral resin is 1000 to 1700, the butyralization degree of the resin is more than 64% and less than 78%, and the residual acetyl group content is less than 6%.

When the degree of polymerization of the polybutyral resin is small, for example, when the thickness is reduced to about 5 μm or less, preferably about 3 μm or less, it tends to be difficult to obtain sufficient mechanical strength. When the degree of polymerization is too large, the surface roughness at the time of sheeting tends to deteriorate. If the butyralization of the polybutyral resin is too low, the solubility in the paint tends to deteriorate, and if it is too high, the surface roughness of the sheet tends to deteriorate. When the amount of remaining acetyl groups is too large, the surface roughness of the sheet tends to deteriorate.

It is preferable to contain the said binder resin in 5 mass parts or more and 6.5 mass parts or less with respect to 100 mass parts of said ceramic powders. When the content of the binder resin is too small, the strength of the sheet decreases and the laminarity (adhesiveness at the time of lamination) tends to deteriorate. When the content of the binder resin is too large, the segregation dispersibility of the binder resin tends to deteriorate, and the surface roughness of the sheet tends to deteriorate.

The particle size of the ceramic powder is preferably 0.01 to 0.5 μm. By refining the particle size of the powder, the green sheet is thinned. Moreover, it is preferable that the non-volatile matter in the coating material for green sheets is 10-48 mass %. Examples of non-volatile components include ceramic powder, binders, plasticizers, dispersants, and the like.

The preparation method of the green sheet that the present invention relates to comprises:

A process of preparing the above-mentioned coating material for the green sheet, and

A step of forming a ceramic green sheet using the above green sheet coating material.

The preparation method of the ceramic electronic component that the present invention relates to comprises:

The process of preparing the above-mentioned coating material for the green sheet,

A process of forming a ceramic green sheet using the above-mentioned paint for green sheet,

A step of drying the above-mentioned green sheet,

a process of laminating the dried green sheet through an internal electrode layer to obtain a green sheet, and

A step of sintering the above-mentioned green sheet.

The green sheet according to the present invention was produced using the coating material for green sheet described above.

According to the present invention, there can be provided a paint, a green sheet, and a method, wherein the paint can produce a green sheet that is extremely thin but has strength capable of withstanding peeling from a support, and has excellent surface smoothness and no pinholes , suitable for thinning and multilayering of electronic components.

Description of drawings

[ Fig. 1] Fig. 1 is a schematic cross-sectional view of a multilayer ceramic capacitor according to an embodiment of the present invention.

[ Fig. 2] Fig. 2 is a sectional view of an essential part showing a manufacturing process of the multilayer ceramic capacitor shown in Fig. 1 .

Detailed ways

The present invention will be described below based on the embodiments shown in the drawings.

First, an overall configuration of a multilayer ceramic capacitor will be described as an embodiment of an electronic component produced using the green sheet coating material (dielectric paste) and the green sheet according to the present invention.

As shown in FIG. 1 , a multilayer ceramic capacitor 2 according to the present embodiment has a capacitor base 4 , a first terminal electrode, and a second terminal electrode 8 . The capacitor base 4 has a dielectric layer 10 and internal electrode layers 12 , and these internal electrode layers 12 are alternately laminated between the dielectric layers 10 . One internal electrode layer 12 laminated alternately is electrically connected to the inner side of the first terminal electrode 6 formed on one end portion of the capacitor body 4 . On the other hand, the other internal electrode layer 12 laminated alternately is electrically connected to the inner side of the second terminal electrode 8 formed on the other end portion of the capacitor base 4 .

The material of the dielectric layer 10 is not particularly limited, and may be made of, for example, a dielectric material such as calcium titanate, strontium titanate, and/or barium titanate. The thickness of each dielectric layer 10 is not particularly limited, but is generally several μm to several hundreds of μm. Especially in the present embodiment, the layer thickness is preferably reduced to 5 μm or less, more preferably 3 μm or less.

The material of the terminal electrodes 6 and 8 is also not particularly limited, and usually copper or copper alloy, nickel or nickel alloy, etc. are used, and silver or an alloy of silver and palladium, etc. can also be used. The thickness of the terminal electrodes 6 and 8 is not particularly limited, but is usually about 10 to 50 μm.

The shape and size of the multilayer ceramic capacitor 2 can be appropriately determined according to the purpose and application. When the multilayer ceramic capacitor 2 is a cuboid, it is generally long (0.6-5.6mm, preferably 0.6-3.2mm)×width (0.3-5.0mm, preferably 0.3-1.6mm)×height (0.1-1.9mm, preferably 0.3-3mm). 1.6mm) or so.

Next, an example of a method of manufacturing the multilayer ceramic capacitor 2 according to the present embodiment will be described.

(1) First, in order to prepare a ceramic green sheet constituting the dielectric layer 10 shown in FIG. 1 after sintering, a dielectric paint (paint for green sheet) is prepared.

Dielectric paint consists of an organic solvent-based paint obtained by kneading a dielectric material (ceramic powder) and an organic vehicle.

As the dielectric raw material, it can be appropriately selected from various compounds composed of composite oxides and oxides, for example, carbonates, nitrates, hydroxides, organometallic compounds, etc., and mixed for use. The dielectric raw material is usually used as a powder having an average particle diameter of 0.1 to 3 μm, preferably 0.4 μm or less. It should be noted that in order to form an extremely thin green sheet, it is desirable to use a fine powder thinner than the thickness of the green sheet.

The organic vehicle refers to a substance in which a binder resin is dissolved in an organic solvent. As the binder resin used for the organic vehicle, in the present embodiment, polyvinyl butyral resin can be used. The degree of polymerization of the polybutyral resin is more than 1000 and less than 1700, the degree of butyralization of the resin is greater than 64% and less than 78%, preferably greater than 64% and less than or equal to 70%, and the amount of residual acetyl groups is less than 6%, preferably 3% %the following.

The degree of polymerization of polybutyral resin can be measured, for example, from the degree of polymerization of polyvinyl acetal resin as a raw material. The degree of butyralization can be measured in accordance with JIS K6728, for example. The amount of residual acetyl groups can be measured in accordance with JIS K6728.

When the degree of polymerization of the polybutyral resin is small, for example, when the thickness is reduced to about 5 μm or less, preferably about 3 μm or less, it tends to be difficult to obtain sufficient mechanical strength. When the degree of polymerization is too large, the surface roughness at the time of sheeting tends to deteriorate. If the butyralization of the polybutyral resin is too low, the solubility in the paint tends to deteriorate, and if it is too high, the surface roughness of the sheet tends to deteriorate. When the amount of remaining acetyl groups is too large, the surface roughness of the sheet tends to deteriorate.

In this embodiment, the organic solvent used for the organic vehicle includes a first solvent having a solubility parameter SP value of 10 or more, and a second solvent having an SP value of 8 or more but less than 10. In the present invention, SP values are heat of vaporization ΔH [cal/mol], gas constant R [cal/K mol], temperature T [K], molecular weight n [g/mol], density ρ [g/ cm ³ ], according to the value defined by ((ΔH-RT)·ρ/n) ^1/2 .

Examples of the first solvent include alcohols such as methanol, ethanol, propanol, and butanol. In addition, examples of the second solvent include ketones, esters, and aromatics, methyl ethyl ketone and methyl isobutyl ketone are preferable for ketones, ethyl acetate and butyl acetate are examples of esters, and examples of aromatics include Toluene, xylene, etc.

The second solvent is contained in an amount of 20 to 60% by mass, preferably 25 to 60% by mass, based on 100% by mass of the total solvent. The mass ratio of the second solvent to the first solvent in the solvent is preferably 0.2 to 2.0, more preferably 0.5 to 1.5.

Preferably, the binder resin is dissolved in an alcohol-based solvent in advance, and a solution is obtained by filtration, and the dielectric powder and other components are added to the solution. Binder resins with a high degree of polymerization are poorly soluble in solvents, and tend to deteriorate the dispersibility of paints in conventional methods. In the method of this embodiment, after dissolving the binder resin with a high degree of polymerization in the above-mentioned good solvent, ceramic powder and other components are added to the solution, so that the dispersibility of the paint can be improved and the generation of undissolved resin can be suppressed . It should be noted that the use of solvents other than the above-mentioned solvents tends to increase the temporal change in the viscosity of the varnish, while the solid content concentration cannot be increased.

The dielectric paint may contain additives selected from various dispersants, plasticizers, antistatic agents, dielectrics, glass frits, insulators, and the like as needed.

In the present embodiment, the dispersant is not particularly limited, but a polyethylene glycol-based nonionic dispersant whose hydrophilicity/lipophilicity balance (HLB) value is 5-6 is preferably used. The SP value of the dispersant is 8-9. The dispersant is preferably added in an amount of 0.5 to 1.5 parts by mass, more preferably in a range of 0.5 to 1.0 parts by mass, relative to 100 parts by mass of the ceramic powder.

When the HLB exceeds the above range, the viscosity of the paint tends to increase and the surface roughness of the sheet tends to increase. When the dispersant is not a polyethylene glycol-based nonionic dispersant, it is not preferable because the viscosity of the paint increases, the surface roughness of the sheet increases, or the elongation of the green sheet decreases.

If the amount of the dispersant added is too small, the surface roughness of the sheet tends to increase, and if too large, the sheet tensile strength and lamination properties tend to decrease.

In this embodiment, it is preferable to use dioctyl phthalate as a plasticizer, and it is preferable to contain 40 to 70 parts by mass of the plasticizer with respect to 100 parts by mass of the binder resin, and more preferably 40 to 60 parts by mass. parts by mass. Compared with other plasticizers, dioctyl phthalate is preferable because it has both sheet strength and sheet elongation, and is particularly preferable because it has low peel strength from a support and is easy to peel. It should be noted that when the content of the plasticizer is too small, the stretchability of the sheet tends to be small and the flexibility tends to be small. On the other hand, if the content is too high, the plasticizer will ooze out from the sheet, segregation of the plasticizer to the sheet will easily occur, and the dispersibility of the sheet will tend to decrease.

In the present embodiment, the dielectric paint contains 1 to 6 parts by mass, preferably 1 to 3 parts by mass, of water with respect to 100 parts by mass of the dielectric powder. When the water content is too small, the change over time of the coating properties due to moisture absorption increases, which is preferable, but the viscosity of the coating tends to increase, and the filtration properties of the coating tend to deteriorate. If the water content is too high, separation or sedimentation of the paint occurs, the dispersibility deteriorates, and the surface roughness of the sheet tends to deteriorate.

In this embodiment, preferably 3 parts by mass to 15 parts by mass, more preferably 5 to 10 parts by mass, of hydrocarbon solvents, industrial gasoline, kerosene, and solvent naphtha are added to 100 parts by mass of the dielectric powder. at least one. By adding these additives, the strength of the sheet and the surface roughness of the sheet can be improved. If the addition amount of these additives is too small, the effect of the addition will be small, and if the addition amount is too large, the strength of the sheet and the surface roughness of the sheet will tend to deteriorate on the contrary.

It is preferable to contain the binder resin in an amount of not less than 5 parts by mass and not more than 6.5 parts by mass with respect to 100 parts by mass of the dielectric powder. When the content of the binder resin is too small, the strength of the sheet decreases and the laminarity (adhesiveness at the time of lamination) tends to deteriorate. When the content of the binder resin is too large, segregation of the binder resin tends to occur, the dispersibility tends to deteriorate, and the surface roughness of the sheet tends to deteriorate.

When the total volume of the ceramic powder, binder resin and plasticizer is 100% by volume, the volume ratio of the dielectric powder is preferably 62.42% to 72.69%, more preferably 63.93% to 72.69%. If the volume ratio is too small, the segregation of the binder tends to occur, the dispersibility tends to deteriorate, and the surface roughness tends to deteriorate. When the volume ratio is too large, the strength of the sheet decreases and the lamination property tends to deteriorate.

In the present embodiment, the dielectric paint preferably contains an antistatic agent, and the antistatic agent is preferably an imidazoline-based antistatic agent. When the antistatic agent is an imidazoline-based antistatic agent, the antistatic effect is small, and the sheet strength, sheet elongation, and bondability tend to deteriorate.

The antistatic agent is contained in an amount of 0.1 to 0.75 parts by mass, more preferably 0.25 to 0.5 parts by mass with respect to 100 parts by mass of the ceramic powder. If the amount of the antistatic agent added is too small, the antistatic effect will be small, and if it is too large, the surface roughness of the sheet will deteriorate, and the strength of the sheet will tend to deteriorate. If the destaticizing effect is too small, static electricity is likely to be generated when the carrier sheet as a support is peeled off from the ceramic green sheet, and defects such as wrinkles on the green sheet are likely to occur.

Using this dielectric coating, a green sheet 10a is formed on a carrier sheet 30 as a support with a thickness of preferably 0.5 to 30 μm, more preferably 0.5 to 10 μm, as shown in FIG. 2 by doctor blade method or the like. After the carrier sheet 30 is formed, the green sheet 10a is dried.

The drying temperature of the green sheet is preferably 50 to 100° C., and the drying time is preferably 1 to 20 minutes. The thickness of the green sheet after drying shrinks by 5 to 25% compared with that before drying. The thickness of the dried green sheet 10a is preferably 3 μm or less.

(2) As shown in FIG. 2, prepare the above-mentioned carrier sheet 30 and another carrier sheet 20, form a peeling layer 22 on it, and form an electrode layer 12a with a predetermined pattern on it. On the surface of the release layer 22 of the electrode layer 12a, a blank pattern layer 24 having substantially the same thickness as that of the electrode layer 12a is formed.

As the carrier sheets 20 and 30, for example, a PET film or the like is used, and silicon or the like is preferably coated in order to improve releasability. The thickness of these carrier sheets 20 and 30 is not particularly limited, but is preferably 5 to 100 μm.

The release layer 22 preferably contains the same dielectric particles as the dielectric constituting the green sheet 10a. This release layer 22 contains a binder, a plasticizer, and a release agent in addition to dielectric particles. The particle size of the dielectric particles may be the same as that of the dielectric particles contained in the green sheet, and is preferably smaller.

In this embodiment, the thickness of the peeling layer 22 is preferably equal to or less than the thickness of the electrode layer 12a, and is preferably set to a thickness of 60% or less, more preferably 30% or less.

The method of coating the release layer 22 is not particularly limited, but since it is necessary to form it extremely thin, a coating method using, for example, a wire bar coater or a die coater is preferable. It should be noted that the adjustment of the thickness of the release layer 22 can be performed by selecting wire bar coaters with different wire diameters. That is, in order to make the coating thickness of the peeling layer 22 thin, a wire bar coater with a small wire diameter can be selected, and conversely, a wire bar coater with a thick wire diameter can be selected in order to form it thicker. The release layer 22 is dried after coating. The drying temperature is preferably 50 to 100° C., and the drying time is preferably 1 to 10 minutes.

As the adhesive used for the release layer 22, for example, acrylic resin, polyvinyl butyral resin, polyvinyl acetal, polyvinyl alcohol, polyolefin, polyurethane, polystyrene, or those made of these copolymers Organic matter, or emulsion composition. The binder contained in the release layer 22 may be the same as or different from the binder contained in the green sheet 10a, but is preferably the same.

It does not specifically limit as a plasticizer used for the peeling layer 22, For example, phthalates, dioctyl phthalate, adipic acid, phosphoric acid ester, glycols etc. are mentioned. The plasticizer contained in the release layer 22 may be the same as or different from the plasticizer contained in the green sheet 10a.

It does not specifically limit as a release agent used for the release layer 22, For example, paraffin, wax, silicone oil, etc. are mentioned. The release agent contained in the release layer 22 may be the same as or different from the release agent contained in the green sheet.

The release layer 22 contains the binder in an amount of preferably 2.5 to 200 parts by mass, more preferably 5 to 30 parts by mass, particularly preferably 8 to 30 parts by mass, based on 100 parts by mass of the dielectric particles.

In the release layer 22, a plasticizer is contained in 0-200 mass parts with respect to 100 mass parts of adhesives, Preferably it is 20-200 mass parts, More preferably, it contains 50-100 mass parts.

The release layer 22 contains a release agent in an amount of 0 to 100 parts by mass, preferably 2 to 50 parts by mass, more preferably 5 to 20 parts by mass, based on 100 parts by mass of the adhesive.

After the release layer 22 is formed on the surface of the carrier sheet, the electrode layer 12a constituting the internal electrode layer 12 after firing is formed in a predetermined pattern on the surface of the release layer 22 . The thickness of the electrode layer 12a is preferably about 0.1 to 2 μm, more preferably about 0.1 to 1.0 μm. The electrode layer 12a may be composed of a single layer, or may be composed of two or more layers with different compositions.

The electrode layer 12 a can be formed on the surface of the release layer 22 by, for example, a thick film forming method such as printing using electrode paint, or a thin film method such as vapor deposition or sputtering. When forming the electrode layer 12a on the surface of the peeling layer 22 by the screen printing method or the gravure printing method which is one kind of thick film method, it operates as follows.

First, prepare electrode paint. Electrode paint is prepared by kneading conductor materials made of various conductive metals or alloys, or various oxides, organometallic compounds, resinates, etc., which become the above-mentioned conductor materials after sintering, and organic vehicles.

As the conductor material used in preparing the electrode paint, Ni or Ni alloy or even their mixture is used. These conductor materials are spherical, scaly, etc., and the shape is not particularly limited, and materials of these shapes may be mixed. The average particle size of the conductor material can be usually about 0.1 to 2 μm, preferably about 0.2 to 1 μm.

Organic vehicles contain binders and solvents. Binders include, for example, ethyl cellulose, acrylic resin, polyvinyl butyral, polyvinyl acetal, polyvinyl alcohol, polyolefin, polyurethane, polystyrene, or their copolymers, etc., particularly preferably Butyral-based such as polyvinyl butyral.

The electrode paint preferably contains 8 to 20 parts by mass of the binder with respect to 100 parts by mass of the conductor material (metal powder). As the solvent, for example, any of known substances such as terpineol, butyl carbitol, and kerosene can be used. The solvent content is preferably about 20 to 55% by mass with respect to the entire paint.

In order to improve bonding properties, it is preferable to contain a plasticizer in the electrode paint. Examples of the plasticizer include phthalates such as benzylbutyl phthalate (BBP), adipic acid, phosphoric acid esters, glycols, and the like. In the electrode paint, the amount of the plasticizer is preferably 10 to 300 parts by mass, more preferably 10 to 200 parts by mass relative to 100 parts by mass of the binder. It should be noted that when the amount of the plasticizer or binder added is too large, the strength of the electrode layer 12a tends to decrease significantly. In addition, in order to improve the transferability of the electrode layer 12a, it is preferable to add a plasticizer and/or a binder to the electrode paint to improve the bonding and/or adhesiveness of the electrode paint.

After or before forming an electrode paint layer with a predetermined pattern on the surface of the peeling layer 22 by printing, a blank pattern layer 24 having substantially the same thickness as the electrode layer 12a is formed on the surface of the peeling layer 22 where the electrode layer 12a is not formed. The blank pattern layer 24 is made of the same material as the green sheet and formed by the same method. The electrode layer 12a and blank pattern layer 22 are dried as necessary. The drying temperature is not particularly limited, but is preferably 70 to 120° C., and the drying time is preferably 5 to 15 minutes.

(3) Thereafter, the electrode layer 12a is bonded to the surface of the green sheet 10a. For this purpose, the electrode layer 12a and the blank pattern layer 24 are pressed together with the carrier sheet 20 on the surface of the green sheet 10a, heated and pressed, and the electrode layer 12a and the blank pattern layer 24 are transferred on the surface of the green sheet 10a. However, the green sheet 10a is transferred on the electrode layer 12a and blank pattern layer 24 as viewed from the green sheet side.

The heating and pressing during the transfer can be performed by pressing and heating by a press, by pressing and heating by a calender roll, and preferably by a pair of rolls. The heating temperature and pressure are not particularly limited.

When a single green sheet 10a is laminated with a single green sheet having electrode layers 12a in a predetermined pattern, a laminated block in which a plurality of electrode layers 12a and green sheets 10a are alternately laminated can be obtained. After that, under this laminated body, a green sheet for an outer layer (thicker laminated body laminated with a plurality of green sheets not formed with an electrode layer) is laminated. Thereafter, a green sheet for an outer layer was similarly formed on the upper side of the laminate, and then finally pressurized.

The final pressurized pressure is preferably 10 to 200 MPa. The heating temperature is preferably 40 to 100°C. Thereafter, the laminate is cut into a predetermined size to form a green sheet. The green sheet is subjected to binder removal treatment, sintering treatment, and then heat treatment for re-oxidizing the dielectric layer.

The binder removal treatment can be performed under normal conditions, but it is particularly preferable to perform the binder removal treatment under the following conditions when a base metal such as Ni or a Ni alloy is used as the conductor material of the internal electrode layer.

Heating rate: 5～300℃/hour,

Keep temperature: 200～400℃,

Holding time: 0.5 to 20 hours,

Environment: Mixed gas of humidified _N2 and _H2 .

The sintering conditions are preferably the following conditions.

Heating rate: 50～500℃/hour,

Holding temperature: 1100～1300℃,

Holding time: 0.5 to 8 hours,

Cooling rate: 50～500℃/hour,

Ambient gas: Mixed gas of humidified _N2 and _H2 .

However, the oxygen partial pressure in the air atmosphere during sintering is preferably 10 ^-2 Pa or less. If it exceeds the above range, the internal electrode layer tends to be oxidized, and if the oxygen partial pressure is too low, the electrode material of the internal electrode layer tends to be abnormally sintered and broken.

The heat treatment after such sintering is preferably performed at a holding temperature or a maximum temperature of 1000°C or higher, more preferably 1000 to 1100°C. When the holding temperature or the maximum temperature during heat treatment is less than the above range, the oxidation of the dielectric material is insufficient, so the insulation resistance life tends to be shortened. If it exceeds the above range, not only the Ni oxidation of the internal electrodes will decrease the capacity, but also the dielectric matrix Response, life tends to be shortened, too. The oxygen partial pressure during heat treatment is higher than the reducing environment during sintering, preferably 10 ⁻³ to 1 Pa, more preferably 10 ⁻² to 1 Pa. If it is less than the above range, reoxidation of the dielectric layer 2a becomes difficult, and if it exceeds the above range, the internal electrode layer 3 tends to be oxidized. Other heat treatment conditions are preferably the following conditions.

Holding time: 0-6 hours,

Cooling rate: 50～500℃/hour,

Environmental gas: humidified _N2 gas, etc.

It should be noted that, for humidifying N ₂ gas or mixed gas, for example, a humidifier can be used. At this time, the water temperature is about 0-75°C. In addition, the binder removal treatment, sintering, and heat treatment may be performed continuously or independently. When it is carried out continuously, it is preferable to change the environment without cooling after the binder removal treatment, then raise the temperature to the holding temperature for sintering for sintering, then cool, and change the environment for heat treatment when reaching the holding temperature for heat treatment. On the other hand, when it is carried out independently, it is preferable to raise the temperature to the holding temperature during the debinder treatment under _N2 gas or humidified _N2 gas atmosphere during sintering, and then change the environment to further increase the temperature and cool to the holding temperature during heat treatment. After that, it is preferable to change to _N2 gas or humidified _N2 gas environment again to continue cooling. During heat treatment, after heating up to the holding temperature under _N2 gas environment, the environment can be changed, and the whole process of heat treatment can also be carried out under humidified _N2 gas environment.

The thus obtained sintered body (device main body 4) is subjected to end face grinding, for example, by barrel grinding, sandblasting, etc., and the terminal electrode coating material is sintered to form terminal electrodes 6, 8. The sintering condition of the terminal electrode paint is preferably, for example, in a humidified mixed gas of N ₂ and H ₂ at 600 to 800° C. for about 10 minutes to 1 hour. Then, a pad layer is formed by electroplating or the like on the terminal electrodes 6 and 8 as necessary. In addition, the paint for terminal electrodes can be prepared similarly to the above-mentioned electrode paint.

The thus-prepared multilayer ceramic capacitor of the present invention is mounted on a printed substrate or the like by soldering or the like, and used for various electric appliances or the like.

According to the method of manufacturing a multilayer ceramic capacitor using the dielectric paint (green sheet paint) and the green sheet according to this embodiment, it is possible to manufacture a green sheet that has a strength capable of withstanding peeling from a support even if the green sheet is extremely thin, and A green sheet with excellent surface smoothness and no pinholes. For example, the thickness of the sintered dielectric layer (sintered green sheet) can be reduced to 5 μm or less, preferably 3 μm or less, more preferably 2 μm or less. The number of laminations can also be increased. Furthermore, defects such as short circuits can be reduced.

In the method for producing a multilayer ceramic capacitor using the dielectric paint (green sheet paint) and the green sheet according to this embodiment, a specific type of dispersant having an HLB within a specific range is used. Therefore, even an extremely thin green sheet of, for example, about 5 μm or less has strength capable of withstanding peeling from a support, and has good bondability and handling properties. In addition, the surface roughness of the sheet is also small, and the lamination property is excellent. For this reason, it is easy to laminate a plurality of green sheets through the electrode layer.

In the method for producing a multilayer ceramic capacitor using the dielectric paint (green sheet paint) and the green sheet according to this embodiment, the dielectric paint contains an antistatic agent, and the antistatic agent is an imidazoline-based antistatic agent. For this reason, even an extremely thin green sheet of, for example, about 5 μm or less can be produced, which has strength capable of withstanding peeling from the carrier sheet as a support, suppresses static electricity generated when peeling from the carrier sheet, and has Good bonding and handling green sheet. In addition, the surface roughness of the sheet is also small, and the lamination property is excellent. For this reason, it is easy to laminate a plurality of green sheets through the electrode layer.

In the method of manufacturing a multilayer ceramic capacitor according to this embodiment, the green sheet is not broken or deformed, and the high-precision dry electrode layer can be easily and accurately transferred onto the surface of the green sheet.

It should be noted that the present invention is not limited to the above-described embodiments, and various changes can be made within the scope of the present invention.

For example, the method of the present invention is not limited to a method of manufacturing multilayer ceramic capacitors, but can also be applied as a method of manufacturing other laminated electronic components.

Example

Hereinafter, the present invention will be described based on more detailed examples, but the present invention is not limited to these examples.

Example 1

Preparation of Coatings for Green Sheets

As the starting material of ceramic powder, use BaTiO ₃ powder (BT-02 Sakai Chemical Industry Co., Ltd.). Prepare ceramic powder subcomponent additives so that relative to the BaTiO ₃ powder 100 parts by mass, (Ba _0.6 Ca _0.4 )SiO ₃ was 1.48 parts by mass, Y ₂ O ₃ was 1.01 parts by mass, MgCO ₃ was 0.72 mass%, Cr ₂ O ₃ was 0.13 mass%, and V _{2 O5} was 0.045 mass%.

At first, only the subcomponent additives are mixed with a ball mill and slurried. That is, the auxiliary component additive (8.8 g in total), ethanol: n-propanol: xylene = 42.5: 42.5: 15 solvent 15 g, dispersant (0.1 g) and binder (subcomponent additive) were mixed with a ball mill. 2% by mass (1.1 g as a varnish addition amount)) and pre-pulverized for 20 hours to obtain a pre-pulverized slurry.

Then, 24 _g of pre-pulverized slurry, 123 g of ethanol, 123 g of n-propanol, 56 g of xylene, 136 g of methyl ethyl ketone, 15 g of mineral spirits, 1.4 g of dispersant, and DOP ( Dioctyl phthalate) 6 g, imidazoline-based antistatic agent 0.8 g, BH-6 varnish (dissolve polyvinyl butyral resin BH- 6) 80 g for 20 hours to obtain a ceramic paint (paint for green sheet).

In addition, as a dispersant, a polyethylene glycol-type nonionic dispersant (HLB=5-6) was used. The SP value of the dispersant is 8-9. As a binder, a 15% varnish of BH6 (polybutyral resin/PVB) manufactured by Sekisui Chemical Co., Ltd. (BH-6 manufactured by Sekisui Chemical Co., Ltd. was dissolved in ethanol/n-propanol = 1:1) was added as a solid content.

The solvent components in this ceramic paint consist of a first solvent consisting of ethanol and n-propanol, and a second solvent consisting of methyl ethyl ketone and xylene. The mass ratio of the second solvent in this solvent was 36 mass % with respect to 100 mass % of all solvents. It should be noted that, as shown in Table 1, the SP value of methyl ethyl ketone is 9.3. Table 1 collectively shows the solubility in polyvinyl butyral resin (PVB) and the solubility in dispersants. In Table 1, ○ indicates excellent solubility, and × indicates insolubility.

The degree of polymerization of the polybutyral resin as the binder resin was 1400, the degree of butyralization thereof was 69%±3%, and the amount of residual acetyl groups was 3±2%. In the ceramic paint, the binder resin was contained in an amount of 6 parts by mass with respect to 100 parts by mass of the ceramic powder (additive containing subcomponents of the ceramic powder). When the total volume of the ceramic powder, the binder resin and the plasticizer in the ceramic paint is taken as 100% by volume, the volume ratio of the ceramic powder is 67.31% by volume.

DOP as a plasticizer was contained in 50 mass parts with respect to 100 mass parts of binder resins in a ceramic coating material. 2 parts by mass of water was contained with respect to 100 parts by mass of the ceramic powder. 0.7 parts by mass of a polyethylene glycol-based nonionic dispersant was contained as a dispersant with respect to 100 parts by mass of the ceramic powder.

To the paint, 5 parts by mass of mineral spirits of at least one of hydrocarbon solvent, industrial gasoline, kerosene, and solvent naphtha was added to 100 parts by mass of the ceramic powder.

The viscosity of the paint was 180 mPa·s. Using a B-type viscometer, using S21 as a rotor, the temperature during measurement is 25° C., and the viscosity of the paint is measured immediately after the paint is dripped. The measurement rotation speed was 50 rpm.

Green sheet preparation

The coating material obtained above was coated on a PET film as a support film with a wire bar coater, and dried to prepare a green sheet having a thickness of 1 μm. The coating speed was 50 m/min, the drying conditions were that the temperature in the drying oven was 60° C. to 70° C., and the drying time was 2 minutes.

Evaluation of Green Sheets

After that, the glossiness of the green sheet was measured. The glossiness was measured using VGS-1D manufactured by Nippon Denshoku Kogyo Co., Ltd., based on JIS Z-8741 (1983) method 3 to measure the surface glossiness of the green sheet. The greater the % gloss, the better the surface smoothness. The results are shown in Table 2. In the measurement of glossiness, 70% or more were judged as good (◯), and the rest were judged as poor (×).

[Table 1] Solvent type SP value Solubility PVB Dispersant alcohol Comparative example 1 ethanol 12.9 ○ x Comparative example 2 1-propanol 11.9 ○ x ketone Example 1 methyl ethyl ketone 9.3 ○ ○ Example 2 methyl isobutyl ketone 8.4 x ○ ester Example 3 ethyl acetate 9.1 x ○ Example 4 N-butyl acetate 8.6 x ○ Aromatic Example 5 Toluene 8.9 swelling ○ Example 6 Xylene 8.9 swelling ○ Comparative example 3 n-Heptanol 7.5 x ○

[Table 2] Solvent type SP amount 2nd solvent/total solvent ratio Gloss determination [wt%] [%] alcohol Comparative example 1 ethanol 12.9 12 58 x Comparative example 2 1-propanol 11.9 12 60 x ketone Example 1 methyl ethyl ketone 9.3 36 73 ○ Example 2 methyl isobutyl ketone 8.4 36 65 ○ ester Example 3 ethyl acetate 9.1 36 70 ○ Example 4 N-butyl acetate 8.6 36 69 ○ Aromatic Example 5 toluene 8.9 36 74 ○ Example 6 Xylene 8.9 36 70 ○ Comparative example 3 n-Heptanol 7.5 12 50 x

[table 3] Types of medium polar solvents 2nd solvent/total solvent ratio 2nd solvent/1st solvent ratio Gloss determination [wt%] [-] [%] Comparative example 4 Xylene 15 0.18 50 x Example 6 Xylene 36 0.56 70 ○ Example 7 Xylene 58 1.46 65 ○ Comparative Example 5 Xylene 66 2.14 55 x

Example 2

A green sheet was prepared in the same manner as in Example 1 except that methyl isobutyl ketone was used instead of methyl ethyl ketone, and the same evaluation was performed. The results are shown in Table 2.

Example 3

A green sheet was prepared in the same manner as in Example 1 except that ethyl acetate was used instead of methyl ethyl ketone, and the same evaluation was performed. The results are shown in Table 2.

Example 4

A green sheet was prepared in the same manner as in Example 1 except that n-butyl acetate was used instead of methyl ethyl ketone, and the same evaluation was performed. The results are shown in Table 2.

Example 5

A green sheet was prepared in the same manner as in Example 1 except that toluene was used instead of methyl ethyl ketone, and the same evaluation was performed. The results are shown in Table 2.

Example 6

A green sheet was prepared in the same manner as in Example 1 except that xylene was used instead of methyl ethyl ketone, and the same evaluation was performed. The results are shown in Table 2. It should be noted that, as shown in Table 3, the mass ratio of the second solvent to the first solvent 1 in the solvent is 0.59.

Comparative example 1

A green sheet was prepared in the same manner as in Example 1 except that ethanol was used instead of methyl ethyl ketone, and the mass ratio of the second solvent was 11% by mass relative to 100% by mass of all solvents, and the same evaluation was performed. The results are shown in Table 2.

Comparative example 2

A green sheet was prepared in the same manner as in Example 1 except that 1-propanol was used instead of methyl ethyl ketone, and the mass ratio of the second solvent was 11% by mass relative to 100% by mass of all solvents, and the same evaluation was performed. The results are shown in Table 2.

Comparative example 3

A green sheet was prepared in the same manner as in Example 1 except that n-heptanol was used instead of methyl ethyl ketone, and the mass ratio of the second solvent was 11% by mass relative to 100% by mass of all solvents, and the same evaluation was performed. The results are shown in Table 2.

Example 7

Except that 58% by mass of the second solvent was contained relative to 100% by mass of the total mass of the solvent, and the mass ratio of the second solvent to the first solvent in the solvent was 1.46, a green sheet was prepared in the same manner as in Example 6. Same evaluation. The results are shown in Table 3.

Comparative example 4

Except containing 15% by mass of the second solvent relative to the total mass of the solvent (100% by mass), and making the mass ratio of the second solvent to the first solvent in the solvent 0.18, a green sheet was prepared in the same manner as in Example 6. Same evaluation. The results are shown in Table 3.

Comparative Example 5

Except that 66% by mass of the second solvent was contained relative to 100% by mass of the total mass of the solvent, and the mass ratio of the second solvent to the first solvent in the solvent was 2.14, a green sheet was prepared in the same manner as in Example 6. Same evaluation. The results are shown in Table 3.

evaluate

As shown in Tables 2 and 3, it can be confirmed that 20 to 60 mass %, preferably 25 to 60 mass %, of the second solvent is contained relative to the total mass of the solvent of 100 mass %, and the mass of the second solvent in the solvent relative to the first solvent is When the ratio is 0.2 to 2.0, preferably 0.5 to 1.5, the glossiness increases and the smoothness of the green sheet surface improves.

Claims (13)

1. green sheet coating, its be contain ceramic powder, be that resin is the adhesive resin and the solvent of principal constituent with butyral, it is characterized in that,

It is that the 1st solvent and above-mentioned SP value more than 10 is more than 8 but the 2nd solvent of less than 10 that above-mentioned solvent contains SP value as solubility parameter,

With respect to the total mass 100 quality % of above-mentioned solvent, contain above-mentioned the 2nd solvent of 20～60 quality %.

2. green sheet coating as claimed in claim 1, wherein, the 2nd solvent phase in the above-mentioned solvent is 0.2～2.0 for the mass ratio of the 1st solvent.

3. green sheet coating as claimed in claim 1 or 2 wherein, further contains dispersion agent, and above-mentioned dispersion agent is that polyoxyethylene glycol is a non-ionic dispersing agent.

4. green sheet coating as claimed in claim 3, wherein, the SP value of above-mentioned dispersion agent is 8～9.

5. as each described green sheet coating in the claim 1～4, wherein, above-mentioned the 1st solvent is an alcohols, and above-mentioned the 2nd solvent contains at least a in ketone, ester class, the fragrant same clan.

6. green sheet coating as claimed in claim 5, wherein, above-mentioned the 1st solvent is to be selected from least a in methyl alcohol, ethanol, propyl alcohol, the butanols, and above-mentioned the 2nd solvent contains and is selected from least a in methylethylketone, methyl iso-butyl ketone (MIBK), ethyl acetate, butylacetate, toluene, the dimethylbenzene.

7. as each described green sheet coating in the claim 1～6; it is characterized in that; above-mentioned butyral resin is the bunching butyral resin; the polymerization degree of above-mentioned bunching butyral resin is more than 1000 below 1700; the butyralization degree of resin is greater than 64% less than 78%, residual ethanoyl quantity not sufficient 6%.

8. as each described green sheet coating in the claim 1～7, wherein, contain the above-mentioned adhesive resin below 6.5 mass parts more than 5 mass parts with respect to above-mentioned ceramic powder 100 mass parts.

9. as each described green sheet coating in the claim 1～8, wherein, the particle diameter of above-mentioned ceramic powder is 0.01～0.5 μ m.

10. as each described green sheet coating in the claim 1～9, wherein, above-mentioned green sheet is 10～48 quality % with the nonvolatile component in the coating.

11. the preparation method of a ceramic green sheet material, it comprises:

Prepare each described green sheet in the claim 1～10 with the operation of coating and

Use the operation of above-mentioned green sheet with coating shaped ceramic green sheet.

12. the preparation method of a ceramic electronic components, it comprises:

Each described green sheet operation of coating in the preparation claim 1～10,

Use the operation of above-mentioned green sheet with coating shaped ceramic green sheet,

Make above-mentioned green sheet exsiccant operation,

By the dried green sheet of interior electrode layer lamination, obtain raw cook operation and

The operation of the above-mentioned raw cook of sintering.

13. use the green sheet that each described green sheet prepares with coating in the claim 1～10.

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